Ngorongoro: Scavengers, Always Picking Up After Someone
Grade Level: 6-9
Related National Standards
Two class periods plus ten to fifteen minutes a day for one week. One period to view selected Ngorongoro video clips, introduce the concept of an ecosystem food chain, and discuss the roles of scavengers and decomposers. Half a class period for students to prepare their "culinary creations." Ten to fifteen minutes a day for one week for student teams to observe, record, and photograph changes to their Decomposed Fruit Shish kebabs. Half a class period for discussion of final activity outcomes.
- Students learn what an ecosystem is.
- Students learn what a food chain is and its purpose.
- Students learn about the various trophic levels within a food chain.
- Students learn about the roles that herbivores, carnivores, scavengers, and decomposers play within an ecosystem.
- Students learn the definition of predator and prey.
- Students learn about some of the other scavengers within the animal kingdom.
- Students work in teams to prepare their decomposed fruit shish kebabs.
- Students work in teams to observe, write in their journals, and photograph all changes that occur to their fruit shish kebabs.
- Students work in teams to mount their team's fruit shish kebab photos sequentially for days three through eight on large poster boards.
- Students write a brief summary of changes that occurred to their team's fruit shish kebab under each photo.
- Student teams display their findings to the entire class for discussion.
An ecosystem is a unit of the environment that consists of interacting living and nonliving elements. Within an ecosystem the sun fuels a food chain that allows energy to pass through different organisms as they feed on one another in a continual cycle of predator and prey.
Think of a food chain as a pyramid with about four different levels, called trophic levels. At the bottom or base of the food chain are plants or producers that through photosynthesis have converted sunlight into chemical energy usable by life. How's that for a solar energy usage! Going up one level, herbivores, like gazelles, zebras, wildebeests, and the less exotic cow feed on plants. Herbivores are the "mass transit" of an ecosystem because they are responsible for transporting energy from the plant to the animal kingdom. Unfortunately for the herbivore this transporting of energy is often a "one-way ticket" because it will eventually become hunted prey and then a meal for a hungry predator. Predators are found at the next level of the food chain. Predators such as lions, cheetahs, and servals are carnivores, animals that eat animal flesh.
There are often two types of carnivores within a food chain, primary and secondary carnivores. A primary carnivore, such as a serval feeds upon a mouse, a herbivore. A secondary carnivore, such as a cheetah, feeds on primary carnivores. Both herbivores and carnivores are consumers they obtain energy by consuming living things via a predator and prey relationship. For more information go to http://www.pbs.org/edens/etosha/fm_foodchain.htm
Ok, so how does this all work together within a food chain, you ask yourself? Using Ngorongoro as an example, grass, a producer, is eaten by a gazelle a herbivore consumer. The gazelle in turn becomes prey and is eaten by a cheetah, a carnivore and another consumer. And circling high above the gorging cheetah, waiting for its chance to eat, glides a vulture yet another type of consumer a scavenger. Scavengers are animals that feed on carrion, the dead flesh of animals, prey, caught by predators. Although generally despised by most human beings, scavengers are vitally important to an ecosystem because they clean it up by removing organic garbage.
Scavengers are found throughout the animal kingdom. On land mammal scavengers include the Alaskan brown bear that often will follow ravens in order to find dead fish to eat; hyenas and jackals scavenge in packs next to one another; and lions and leopards will scavenge when their hunt is unsuccessful often taking prey caught by another animal predator. In the air bird scavengers include California condors that eat carrion; crows that often eat road kill; Marabou storks that eat dead fish and reptiles; seagulls that will eat anything, and of course vultures with their keen eyesight for spotting prey, long necks and bald heads that allow easy access into a carcass, make the vulture a gruesomely adapted scavenger. Underwater scavengers include carnivorous hermit crabs that make their homes in discarded mollusk shells and live on sea bottoms ranging from the deep sea to the sea shore; marine eels eat dead fish and crustaceans; sharks that eat dead or wounded fish; and remoras, a permanent dining guest, that use their suction cup heads to fasten themselves to a larger fish, or host, and eat the host's parasites and leftovers. Anyone still hungry? For more information on these and other animals go to these sites: http://animalatlas.com.
After scavengers have eaten their fill of dead organic material, the gazelle, decomposers have a turn feasting. There are two types of decomposers, macrodecomposers and microdecomposers. Macrodecomposers are primarily earthworms and insect larvae. Microdecomposers are bacteria and fungi. Both of these decomposers further break down organic matter and extract nutrients. The nutrients are then returned to the soil and used by plants to begin the food chain again. Check out http://www.pbs.org/edens/etosha/fm_dinner.htm for another food chain example.
- Heavy-duty bamboo skewers, 12-inches or longer (Usually found in the cooking utensil aisle of most large grocery stores.)
- Apples, bananas, pears, and peaches
- Sharp knives
- Aluminum foil
- Old newspapers
- Disposable cameras (one per team)
- Smocks (optional, however, it could get messy.)
- Trash bags (for waste)
- Composition journals
- 6-inch strips of ribbon in a variety of colors
- Large poster boards
- Gluesticks or scotch tape
- A shady bare section of ground near small plants or grass
Procedure (Day One)
Procedure (Day Two)
- Group your students into teams of 4 to 6 people.
- Tell them to brainstorm what they know about food chains; the roles of producers, consumers, and decomposers; and to record their responses.
- Have a spokesperson from each team tell the class the results of their team's food chain brainstorming session.
- Write their responses on the boardYou may want to organize their responses into categories depending upon the variety and number of responses generated.
- Show Ngorongoro food chain related video clips:
(12:00-14:00) - This segment highlights an airborne vulture scanning the ground for carrion; then joining other vultures feasting on a hippotmus carcus.
16:00-21:00) - This segment highlights the predator and prey concept via a pair of cheetahs hunting gazelles.
(31:00-33:00) - This segment highlights food chains, producers, and consumers by showing wildebeests, herbivores, eating new grass shoots.
(38:00-40:00) - This segment highlights synchronized wildebeest births that draw more predators to the herd but provide the best chance for overall wildebeest survival. Reinforces the concepts of predator and prey, as well as the roles of herbivores and carnivores.
(43:00-45:00) - This segment highlights a cheetah hunting, chasing, and downing a wildebeest only to lose it to a scavenging hyena.
(50:00-51:00) - This segment highlights that lions are threatened by disease due to inbreeding, which threatens to upset the vital predator and prey balance within the Ngorongoro Crater.
(51:00-52:00) - This segment highlights the roles of herbivores and carnivores within a food chain by showing a serval, a conivore and a consumer, hunting and killing a mouse, a herbivore and a consumer.
- Using their brainstorming responses and the video clips as springboards tell your students to take notes in their journals as you fill in the knowledge gaps by presenting more information on how a food chain works and the roles of various organisms within an ecosystem's food chain. (For minimum assessment purposes your students should record in their journals a brief description of each trophic level within a food chain.)
- End presentation with an announcement about tomorrow's decomposed fruit shish kebab activity.
Procedure (Days Three to Eight)
- Have students reassemble into their teams.
- Distribute and spread newspapers onto tabletop surfaces.
- Distribute and spread aluminum foil onto a section of the tabletop.
- Distribute fruit, knives, and bamboo skewers.
- Distribute smocks, trash bags, ribbon, composition journals, and disposable cameras.
- Cut all fruit into large chunks and leave the skin on everything, including the bananas.
- Push skewer through the middle of all four chunks of fruit
(HINT: You may want to use the apple as the base and place the other three fruit chunks on top of it.)
- Tie ribbon in a bow around the skewer so that each team can readily identify their fruit shish kebab.
- Shove the skewer into the ground firmly leaving enough clearance so that the base of the skewer, the apple, is at least 3-inches above the groundAll skewers should be placed as far apart from each other as possible.
- Eat remaining fruit.
- Clean up the classroom.
- Distribute composition journals and disposable cameras.
- Explain to students that for the next five school days each team is to once a day observe their team's fruit shish kebab, record all changes to the fruit in their composition journals, and take at least two photos at different anglesChanges to the fruit can include bite marks, breaks in the skin, decay odors, appearance of insects or worms, and the appearance of molds or fungi.
Procedure (Day Nine)
- Have each team for 10 to 15 minutes once a day observe their fruit shish kebab, record all changes to the fruit in their composition journals, and take at least two photos at different angles.
(HINT: When taking photos include a small index card with the date on it to more accurately document all changes to the fruit shish kebabs.)
- On the eighth day after recording and photographing final changes to their fruit shish kebabs, have each team remove their decomposed fruit shish kebab from the ground (Serve at room temperature with a garnish of Pepto-Bismol! Or toss into a compost pile.)
- At the end of the eighth day take all disposable cameras to be developed overnight. (Make sure to mark each team's camera for identification and distribution purposes.)
Procedure (Day Ten)
- Return photos to each team.
- Distribute large poster boards, glue sticks, and or scotch tape.
- Have each team mount their photos sequentially for days three through eight.
- Underneath each photo have students write a brief summary about all of the changes to their fruit shish kebab that they observed each day.
- Display each team's poster.
- Discuss final activity outcomes.
- Collect all student composition journals for assessment.
For Younger Students
Observe decay first hand all year long and improve your school's soil by building an onsite compost pile. Have your students research composting in the library and on the Internet at http://www.epa.gov/epaoswer/non-hw/compost/. After their research is completed, build a school compost pile as a class project. Organize other students in classrooms throughout the school to contribute to the compost pile by frequently bringing food wastes and lawn trimmings from home.
For Older Students
Even though scavengers, especially vultures, serve a vital purpose within an ecosystem they suffer from a negative image problem. Conduct a literary search of myths, fables, and folktales that involve vultures from as many cultures as possible to see how other cultures view vultures. Design a public education campaign to improve the vulture's image within your school and community. Elements of the vulture public education campaign can include news releases, feature stories, public service announcements for radio and television, and advertisements.
Divide students into teams of six. Have each team research another ecosystem and identify the major organisms, plants and animals, found at each level of the food chain. Using the school's media center or a video camera from home, make a mini documentary about your ecosystem's food chain. Team members can serve as documentary writers, prop designers, narrators, camera operators, and other typical pre and postproduction tasks. Contact your local cable television station to arrange for broadcast.
- Evaluate your students on their ability to work together in teams to observe, document, and present the changes that occurred to their fruit shish kebabs.
- Evaluate the writing and content of each student's journal entries for this lesson and activity.
Anderson, Stanley, et al., "Environmental Science," Merrill Publishing Company, 1987
Banister, Keith, "The Encyclopedia of Aquatic Life," Facts on File, Inc., 1993
Dasmann, Raymond, "Environmental Conservation," John Wiley & Sons, 1984
Vesilind, P., "Environmental Pollution and Control," Butterworth-Heinemann, 1990
PBS Online Sites:
Nature: Showdown at Grizzly River
Nature: The Secret World of Sharks and Rays
NOVA: Island of the Sharks
Nova: Shark Attack
Secrets of the Ocean Realm: Sharks
The Living Edens: Etosha
The Living Edens: Kamchatka
The Living Edens: Namib
Other Online Sites:
Monterey Bay Aquarium: Sharks
Electronic Library - Raccoons
African Wildlife Foundation: Hyenas
Travel Channel - Africa - Tanzania
Microsoft et al, "Encarta '96 Encyclopedia," Microsoft Corporation, 1996
Related National Standards
This lesson addresses the following national content standards found at http://www.mcrel.org:
Knows about the diversity and unity that characterize life.
Knows ways in which living things can be classified (e.g., taxonomic groups of plants, animals, and fungi; groups based on the details of organisms, internal and external features; groups based on functions served within an ecosystem such as producers, consumers and decomposers.
Understands how species depend on one another and on the environment for survival.
Knows ways in which species interact and depend on one another in an ecosystem (e.g., producer/consumer, predator/prey, parasite/host relationships that are mutually beneficial or competitive.
Knows that all individuals of a species that occur together at a given place and time are a population, and all populations living together and the physical factors with which they interact compose an ecosystem.
Knows relationships that exist among organisms in food chains and food webs.
Understands the cycle of matter and flow of energies through the living environment.
Knows how energy is transferred through food webs in an ecosystem (e.g., energy enters ecosystems as sunlight, and green plants transfer this energy into chemical energy through photosynthesis, this chemical energy is passed from organism to organism; animals get energy from oxidizing their food, releasing some of this energy as heat.)
Knows how matter is recycled within ecosystems (e.g., matter is transferred from one organism to another repeatedly, and between organisms and their physical environment; the total amount of matter remains constant, even though its form and location change.
and the following national science content standards found at http://www.nap.edu/readingroom/books/nses/html/:
Develop an understanding of structure and function in living systems.
Develop an understanding of regulation and behavior.
Develop an understanding of populations and ecosystems.
Develop an understanding of diversity and adaptations of organisms.